Rotary kiln for burning cement, ore, and similar materials



April 25, 1933. D. PARKER 1,905,744

ROTARY KILN FOR BURNING CEMENT, ORE, AND SIMILAR MATERIALS Filed Feb. 6, r 1931 2 Sheets-Sheet l T 'fxflfl m q I IR April 25, 1933. L. D. PARKER 1,905,744

- ROTARY KILN FOR BURNING CEMENT, ORE, AND SIMILAR MATERIALS Filed Feb. 6, 1931 2 Sheets-Sheet 2 Patented Apr. 25, 1933 UNITED STATES r 'reNT GFFICE LIONEL DOUGLAS PARKER, OF BARROW-IN-FURNESS, ENGLAND, ASSIGNOR TO VICKERS- ARMSTRONGS LIMITED, OF WESTMINSTER; ENGLAND, A BRITISH COMPANY no'rAnY KILn non BURNING cEMnnn'oRE; nn SIMILAR, MATERIALS Application filed February 6, 1931, Serial No.

This invention relates to rotary kilns for burning cement, ore and similar materials, of the kind provided with longitudinally arranged heat recuperating'tubes or hollow members which are disposed around the front portion of thekiln or a forward extension thereof, the said tubes communicating at their forward ends by means of transverse hollow members or tubes with the interior of the kiln for the entry into the said heat recuperating tubes of the hot material or clinker which passes forwardly through the latter tubes in the opposite direction to the entering air so that an interchange of heat takes place resulting in the partial cooling of the clinker and the heating of the air. The invention is particularly, although not exclusively, applicable to the general form of kiln and recuperator described in the specification of my prior English Patent No. 262,525 whether the tubes or hollow members be made tapered, or be made cylindrical with their axes inclined to the axis of the kiln as described in the said specification or whether they be made cylindrical and arranged parallel to the axis of the kiln as in other known constructions. The chief object of the present invention is to prevent the material that has entered the heat recuperating tubes from returning to the kiln through the transverse communicating tubes; this return of the material, which is liable to occur when the heat recuperating tubes approach or reach positions above the axis of the kiln during the rotation of the latter, retards the rate of delivery of the clinker and thus reduces the efficiency of the kiln.

According to the present invention the forward end of each heat recuperating tube is made of conical or trunco-conical formation with its apex or smaller end at the front or is otherwise so formed as to provide an inclined surface down which the hot material falls by gravity at all positions of the tube during the rotation of the kiln, and at or near the base of the cone or forward end there is provided an inwardly extending lip or projection which shields the outlet opening of the transverse communicating tube and acts as a barrier to the return of any of the-ma- 513,904, and in Great Britain July 19, 1930.

terial through the latter tube. The feeding movement of the material effected by the cone or its equivalent and the barrier constituted by the lip or projection effectively prevent the material from returning to the kiln. The-said lip'or projection may conveniently be a continuation or extension of the transverse communicating tube.

The aforesaid transverse communicating tubes have heretofore either been curved or have been arranged radially with respect to the axis of the kiln and it has been found that these tubes rapidly become worn away owing to the impact of the material on the inner Walls thereof; this leads to a-dangerous condition as the said tubes form part of the means connecting the heat recuperating tubes to the kiln and also results in con siderable expense and loss of time in effecting repairs. In order to avoid this I arrange the said communicating tubes at such an angle that the material falls freely through them without any part or any substantial part thereof touching the inner walls. The inner walls of the transverse communicating tubes are therefore not subjected to wear but the material falls directly upon the aforesaid conical or similar ends and at the place of impact each end is provided with a removable portion or door which, when-wear takes place, can readily be replaced by another.

In order that the said invention may be clearly understood and readily carried into effect, the same will now be described more fully with reference to the accompanying drawings, in which Figure 1 is a sectional side elevation showing a constructional form of my improvements,

Figure 2 is a transverse section, viewed from the front, of the upper part of Figure 1, the right hand portion of Figure 2' being a section taken approximately on the line 1, 1 of Figure 1 and the left hand portion being a section taken approximately on the line 2, 2 of Figure 1, and

Figure 3 is a localsection, viewed from the front, taken approximately on the line 3, 3 of Figure 1.

A is the front end of the kiln the axis of which is, as is customary, arranged at a small angle to the horizontal with the front end lower than the rear end. B, B are the longitudinally arranged heat recuperating tubes or hollow members disposed around a'cylinder A constituting an exten sion of the kiln in front of the burning zone (the said cylinder thus forming part of the recuperator as the material is partly cooled therein) and B B are the transverse hollow members or tubes which establish communication between'the front ends of the tubes B, Band the interior of the cylinder A As shown the tubes B, B are arranged with their axes parallel to the axis of the kiln and in this case each: tube has a feeding device comprising two sets B B of helical projections of which the elements of the set B near the front end have a slow or small pitch and the elements of, the set B furtherf away from the front end have a quick or large pitch so as to cascade the material asfwell as feeding it 1 along the tube. When the tubes B, Bare tapered or made cylindrical with their axes suitably inclined to the axis of the kiln as aforesaid, these feeding devices are not necessary. V

The forward end B of eachtube B is, as shown, made of conical or trunco-conical formation with its apex or smaller end at the front, and at or near the base of the cone there is an inwardly projecting lip or projection B which is a continuation or extension of the tube B this continuation or extension may be cut away as shown in Figure 3 on the side that is uppermost during the upward movement of the tube B. The material from the interior of the cylinder A falls on the conicalend B and moves rearwards down its surface and during the upward movement of the tube B the movement imparted to the material by the conical end continues, the outlet end of the tube B being all the time protected by the extension B so that the material cannot be returned by gravity to the cylinder A even when the tube B reaches its uppermost position.

Each cone B is provided with a removable portion or door b at the place where the material falls thereon so that, when wear takes place, this portion or door can be replaced by another. For the reason hereinbefore described each of the transverse communicating tubes B is arranged at such an angle that the material falls freely through it without any part or sub stantial part of the said material touching the inner wall of the said tube. The angle to obtain this effect has been found to be about 10 to the radial position as shown in Figure 3 when, as is usually the case and as is illustrated, the cylinder A is provided with an internal annular rib A which diroots the material so that it has a prescribed path when overflowing the said rib.

Instead of the forward ends of the heat recuperating tubes being made of conical or trunco-conical shape, they may be hemispherical, bulb shaped or pyramidal with any number of flat or curved sides, any of these shapes being truncated if desired.

What I claim and desire to secure by- Letters Patent of the United States is 1. In a rotary kiln, the combination of a plurality of hollow heat recuperating members disposed longitudinally around the front portion of the kiln, transverse hollow members which establish communication between the interior of the kiln and the forward ends of the latter hollow members, an inclined surface at the forward end of each heat recuperating member, down which surface the hot material falls by gravity at all positions of said member during the rotation of the kiln, and inwardly extending projections which shield the outlet openings of the transverse members and act'as barriers to the return of the material through these members.

2. In a rotary kiln, the combination of a plurality of hollow heat recuperating members disposed longitudinally around the front portion of the kiln, transverse hollow members which establish communication between the interior of the kiln and the forward ends of the latter hollow members, an inclined surface at the forward end of each heat recuperating member, down which surface the hot material falls by gravity at all positions of said member during the rotation of the kiln, and extensions of said transverse members, these extensions serving to shield the outlet openings of the transverse members and act as barriers to the return of the material through these members.

3. In a rotary kiln, the combination of a plurality of hollow heat recuperating members disposed longitudinally around the front portion of the kiln, transverse hollow members which establish communication between the interior of the kiln and the forward ends of the latter hollow members and which are arranged atsuch an angle that the material falls freely through them without any part or any substantial part thereof touching the inner walls, an inclined surface at the forward end of each heat recuperating member down which surface the hot material falls by gravity at all positions of said member during the rotation of the kiln and inwardly extending projections which shield the outlet openings of the transverse members and act as barriers to the return of the material through these members.

4. In a rotary kiln, the combination of a plurality of hollow heat recuperating members disposed longitudinally around the front portion of the kiln, transverse hollow members which establish communication between the interior of the kiln and the forward ends of the latter hollow members, a conical or trunco-conical formation of the forward end of each heat recuperating member to provide an inclined surface down which the hot material falls by gravity at all positions of said member during the rotation of the kiln, and inwardly extending projections which shield the outlet openings of the transverse members and act as barriers to the return of the material through these members.

5. In a rotary kiln, the combination of a cylinder constituting an extension of the kiln in front of the burning zone, a plurality of hollow heat recuperating members disposed longitudinally around said cylinder, transverse hollow members which establish communication between the interior of said cylinder and the forward ends of the latter hollow members, an inclined surface at the forward end of each heat recuperating member, down which surface the hot material falls by gravity at all positions of said member during the rotation of the kiln, and inwardly extending projections which shield the outlet openings of the transverse members and act as barriers to the return of the material through these members.

6. In a rotary kiln, the combination with the elements claimed in claim 1, of a removable portion at the forward end of each heat pecuperating member where the material alls.

. 7. In a rotary kiln, the combination with the elements claimed in claim 2, of a removable portion at the forward end of each heat necuperating member where the material falls.

8. In a rotary kiln, the combination with the elements claimed in claim 3, of a removable portion at the forward end of each heat pecuperating member where the material alls.

9. In a rotary kiln, the combination with the elements claimed in claim 4, of a removable portion at the forward end of each heat ieirilperating member where the material 10. In a rotary kiln, the combination with the elements claimed in claim 5, of a removable portion at the forward end of each heat recuperating member where the material falls.

LIONEL DOUGLAS PARKER. 

